Operator restraint systems that include a seatbelt have been widely employed in machines, such as construction equipment, mobile vehicles, etc., to protect operators during operations of these machines. In some circumstances, operators either do not buckle the seatbelt, or they buckle the seatbelt incorrectly. Various operator restraint systems have been developed to detect whether the seatbelt is buckled, and to generate warning signals, such as visible and/or audible signals, to remind the operators to employ the seatbelt during machine operation. However, some conventional operator restraint systems can be bypassed by the operator, for example, by buckling the seatbelt behind his/her back. In such a situation, the seatbelt may be buckled, but it may be buckled in an incorrect manner. Conventional operator restraint systems may fail to detect such a situation. A seatbelt buckled behind an operator's back will be ineffective to render protection to the operator.
A safety belt warning device is described in U.S. Patent Application Publication No. 2008/0169916 A1 (the '916 publication) to Lai published on Jul. 17, 2008. The safety belt warning device of the '916 publication includes a warning member electrically coupled to a sensing member. The sensing member includes a magnetic element installed on a first buckle member of a safety belt buckle and a magnetically-activated control element installed on a second buckle member of the safety belt buckle. The warning member generates a warning signal in the form of sound, light, or both, when the first buckle member and the second buckle member are not engaged.
Although the safety belt warning device of the '916 publication may provide reminders to an operator for buckling the safety belt, it may be problematic in some situations. For example, the operator may buckle the belt behind his/her back, and the safety belt warning device of the '916 publication may be ineffective in detecting that the safety belt has not been properly employed.
The present disclosure is directed toward improvements in the existing technology.